Electroless Ni-P/Ni-W-P thin-film resistors for MCM-L based technologies

A novel technique of fabricating MCM-L compatible integrated resistors on large area substrates is presented. Electroless plated Ni-P/Ni-W-P alloys are used to achieve resistivity values in the range of 5-50 ohm/square and absolute temperature coefficient of resistivity below 50 ppm/°C, which is sufficient to satisfy many resistor application needs. Fine line structures (<50 μm linewidth) are achieved by a three step process: electroless plating a thin (100-200 Å) seed layer on patterned photoresist; lift-off of regions of the seed layer by dissolution of the photoresist; and electroless plating of the resultant structures in the seed layer to the desired thickness to achieve a specific sheet resistance. Improvements in seeding uniformity of the initial blanket seed layer were achieved by use of an organosilane-based surface treatment prior to deposition, as well as tight control of temperature across the substrate during plating. A test vehicle consisting of various resistor structures to evaluate electrical and mechanical properties, processing conditions, and reliability was designed and fabricated. Electrical properties, (including scattering parameters (S-parameters) of the resistor structures up to 20 GHz), temperature coefficient of resistivity (TCR), and power handling capabilities of the resistor structures on different substrates are presented